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- Pd0–Ov–Ce3+ Interfacial Sites with Charge Redistribution for Enhanced
Hydrogenation of Methyl Oleate to Methyl Stearate-
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Abstract: Abstract Improving the efficiency of metal/reducible metal oxide interfacial sites for hydrogenation reactions of unsaturated groups (e.g., C=C and C=O) is a promising yet challenging endeavor. In our study, we developed a Pd/CeO2 catalyst by enhancing the oxygen vacancy (OV) concentration in CeO2 through high-temperature treatment. This process led to the formation of an interface structure ideal for supporting the hydrogenation of methyl oleate to methyl stearate. Specifically, metal Pd0 atoms bonded to the OV in defective CeO2 formed Pd0–OV–Ce3+ interfacial sites, enabling strong electron transfer from CeO2 to Pd. The interfacial sites exhibit a synergistic adsorption effect on the reaction substrate. Pd0 sites promote the adsorption and activation of C=C bonds, while OV preferably adsorbs C=O bonds, mitigating competition with C=C bonds for Pd0 adsorption sites. This synergy ensures rapid C=C bond activation and accelerates the attack of active H* species on the semi-hydrogenated intermediate. As a result, our Pd/CeO2-500 catalyst, enriched with Pd0–OV–Ce3+ interfacial sites, demonstrated excellent hydrogenation activity at just 30 °C. The catalyst achieved a Cis–C18:1 conversion rate of 99.8% and a methyl stearate formation rate of 5.7 mol/(h·gmetal). This work revealed the interfacial sites for enhanced hydrogenation reactions and provided ideas for designing highly active hydrogenation catalysts.
PubDate: 2024-08-01
- RuO2/CoMo2Ox Catalyst with Low Ruthenium Loading for Long-Term Acidic
Oxygen Evolution-
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Abstract: Abstract We must urgently synthesize highly efficient and stable oxygen-evolution reaction (OER) catalysts for acidic media. Herein, we constructed a series of Ti mesh (TM)-supported RuO2/CoMoyOx catalysts (RuO2/CoMoyOx/TM) with heterogeneous structures. By optimizing the ratio of Co to Mo, RuO2/CoMo2Ox/TM with low Ru loading (0.079 mg/cm2) achieves remarkable OER performance (η = 243 mV at 10 mA/cm2) and high stability (300 h @ 10 mA/cm2) in 0.5 mol/L H2SO4 electrolyte. The activity of RuO2/CoMoyOx/TM can be maintained for 50 h at 100 mA/cm2, and a water electrolyzer with RuO2/CoMo2Ox/TM as anode can operate for 40 h at 100 mA/cm2, suggesting the remarkable OER durability of RuO2/CoMoyOx/TM in acidic electrolyte. Owing to the heterogeneous interface between CoMo2Ox and RuO2, the electronic structure of Ru atoms was optimized and electron-rich Ru was formed. With modulated electronic properties, the dissociation energy of H2O is weakened, and the OER barrier is lowered. This study provides the design of low-cost noble metal catalysts with long-term stability in an acidic environment.
PubDate: 2024-08-01
- Comparison of Perovskite Systems Based on AFeO3 (A = Ce, La, Y) in CO2
Hydrogenation to CO-
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Abstract: Abstract CO2 is the most cost-effective and abundant carbon resource, while the reverse water–gas reaction (rWGS) is one of the most effective methods of CO2 utilization. This work presents a comparative study of rWGS activity for perovskite systems based on AFeO3 (where A = Ce, La, Y). These systems were synthesized by solution combustion synthesis (SCS) with different ratios of fuel (glycine) and oxidizer (φ), different amounts of NH4NO3, and the addition of alumina or silica as supports. Various techniques, including X-ray diffraction analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, energy-dispersive X-ray spectroscopy, N2-physisorption, H2 temperature-programmed reduction, temperature-programmed desorption of H2 and CO2, Raman spectroscopy, and in situ FTIR, were used to relate the physicochemical properties with the catalytic performance of the obtained composites. Each specific perovskite-containing system (either bulk or supported) has its own optimal φ and NH4NO3 amount to achieve the highest yield and dispersion of the perovskite phase. Among all synthesized systems, bulk SCS-derived La–Fe–O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption, outperforming La–Fe–O produced by solgel combustion (SGC). CO2 conversion into CO at 600 °C for bulk ferrite systems, depending on the A-cation type and preparation method, follows the order La (SGC) < Y < Ce < La (SCS). The differences in properties between La–Fe–O obtained by the SCS and SGC methods can be attributed to different ratios of oxygen and lanthanum vacancy contributions, hydroxyl coverage, morphology, and free iron oxide presence. In situ FTIR data revealed that CO2 hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La–Fe–O, obtained by the SCS method. γ-Al2O3 improves the dispersion of CeFeO3 and LaFeO3 phases, the specific surface area, and the quantity of adsorbed H2 and CO2. This led to a significant increase in CO2 conversion for supported CeFeO3 but not for the La-based system compared to bulk and SiO2-supported perovskite catalysts. However, adding alumina increased the activity per mass for both Ce- and La-based perovskite systems, reducing the amount of rare-earth components in the catalyst and thereby lowering the cost without substantially compromising stability.
PubDate: 2024-08-01
- Numerical Simulation of the Parallel Gap Resistance Welding Process of a
Solar Cell and Mo/Pt/Ag Interconnector-
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Abstract: Abstract Energy for space vehicles in low Earth orbit (LEO) is mainly generated by solar arrays, and the service time of the vehicles is controlled by the lifetime of these arrays, which depends mainly on the lifetime of the interconnects. To increase the service life of LEO satellites, molybdenum/platinum/silver (Mo/Pt/Ag) laminated metal matrix composite (LMMC) interconnectors are widely used in place of Mo/Ag LMMC and Ag interconnectors in solar arrays. A 2D thermal–electrical–mechanical coupled axisymmetric model was established to simulate the behavior of the parallel gap resistance welding (PGRW) process for solar cells and Mo/Pt/Ag composite interconnectors using the commercial software ANSYS. The direct multicoupled PLANE223 element and the contact pair elements TARGE169 and CONTA172 were employed. A transitional meshing method was applied to solve the meshing problem due to the ultrathin (1 μm) intermediate Pt layer. A comparison of the analysis results with the experimental results revealed that the best parameters were 60 W, 60 ms, and 0.0138 MPa. The voltage and current predicted by the finite element method agreed well with the experimental results. This study contributes to a further understanding of the mechanism of PGRW and provides guidance for finite element simulation of the process of welding with an ultrathin interlayer.
PubDate: 2024-08-01
- Oxidation Evolution and Activity Origin of N-Doped Carbon in the Oxygen
Reduction Reaction-
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Abstract: Abstract N-doped carbon materials, with their applications as electrocatalysts for the oxygen reduction reaction (ORR), have been extensively studied. However, a negletcted fact is that the operating potential of the ORR is higher than the theoretical oxidation potential of carbon, possibly leading to the oxidation of carbon materials. Consequently, the influence of the structural oxidation evolution on ORR performance and the real active sites are not clear. In this study, we discover a two-step oxidation process of N-doped carbon during the ORR. The first oxidation process is caused by the applied potential and bubbling oxygen during the ORR, leading to the oxidative dissolution of N and the formation of abundant oxygen-containing functional groups. This oxidation process also converts the reaction path from the four-electron (4e) ORR to the two-electron (2e) ORR. Subsequently, the enhanced 2e ORR generates oxidative H2O2, which initiates the second stage of oxidation to some newly formed oxygen-containing functional groups, such as quinones to dicarboxyls, further diversifying the oxygen-containing functional groups and making carboxyl groups as the dominant species. We also reveal the synergistic effect of multiple oxygen-containing functional groups by providing additional opportunities to access active sites with optimized adsorption of OOH*, thus leading to high efficiency and durability in electrocatalytic H2O2 production.
PubDate: 2024-08-01
- Photophysical Properties and Photovoltaic Performance of Sensitizers with
a Bipyrimidine Acceptor-
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Abstract: Abstract Molecular engineering is a crucial strategy for improving the photovoltaic performance of dye-sensitized solar cells (DSSCs). Despite the common use of the donor–π bridge–acceptor architecture in designing sensitizers, the underlying structure–performance relationship remains not fully understood. In this study, we synthesized and characterized three sensitizers: MOTP-Pyc, MOS2P-Pyc, and MOTS2P-Pyc, all featuring a bipyrimidine acceptor. Absorption spectra, cyclic voltammetry, and transient photoluminescence spectra reveal a photo-induced electron transfer (PET) process in the excited sensitizers. Electron spin resonance spectroscopy confirmed the presence of charge-separated states. The varying donor and π-bridge structures among the three sensitizers led to differences in their conjugation effect, influencing light absorption abilities and PET processes and ultimately impacting the photovoltaic performance. Among the synthesized sensitizers, MOTP-Pyc demonstrated a DSSC efficiency of 3.04%. Introducing an additional thienothiophene block into the π-bridge improved the DSSC efficiency to 4.47% for MOTS2P-Pyc. Conversely, replacing the phenyl group with a thienothiophene block reduced DSSC efficiency to 2.14% for MOS2P-Pyc. Given the proton-accepting ability of the bipyrimidine module, we treated the dye-sensitized TiO2 photoanodes with hydroiodic acid (HI), significantly broadening the light absorption range. This treatment greatly enhanced the short-circuit current density of DSSCs owing to the enhanced electron-withdrawing ability of the acceptor. Consequently, the HI-treated MOTS2P-Pyc-based DSSCs achieved the highest power conversion efficiency of 7.12%, comparable to that of the N719 dye at 7.09%. This work reveals the positive role of bipyrimidine in the design of organic sensitizers for DSSC applications.
PubDate: 2024-07-25
- Insight into the Alkali Resistance Mechanism of CoMnHPMo Catalyst for NH3
Selective Catalytic Reduction of NO-
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Abstract: Abstract The existence of alkali metals in flue gases originating from stationary sources can result in catalyst deactivation in the low-temperature selective catalytic reduction (SCR) of nitrogen oxides (NOx). It is widely accepted that alkali metal poisoning causes damage to the acidic sites of catalysts. Therefore, in this study, a series of CoMn catalysts doped with heteropolyacids (HPAs) were prepared using the coprecipitation method. Among these, CoMnHPMo exhibited superior catalytic performance for SCR and over 95% NOx conversion at 150–300 ℃. Moreover, it exhibited excellent catalytic activity and stability after alkali poisoning, demonstrating outstanding alkali metal resistance. The characterization indicated that HPMo increased the specific surface area of the catalyst, which provided abundant adsorption sites for NOx and NH3. Comparing catalysts before and after poisoning, CoMnHPMo enhanced its alkali metal resistance by sacrificing Brønsted acid sites to protect its Lewis acid sites. In situ DRIFTS was used to study the reaction pathways of the catalysts. The results showed that CoMnHPMo maintained high NH3 adsorption capacity after K poisoning and then reacted rapidly with NO intermediates to ensure that the active sites were not covered. Consequently, SCR performance was ensured even after alkali metal poisoning. In summary, this research proposed a simple method for the design of an alkali-resistant NH3-SCR catalyst with high activity at low temperatures.
PubDate: 2024-07-23
- Enhanced Ethylene Production from Electrocatalytic Acetylene
Semi-hydrogenation Over Porous Carbon-Supported Cu Nanoparticles-
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Abstract: Abstract Electrocatalytic semi-hydrogenation of acetylene (C2H2) over copper nanoparticles (Cu NPs) offers a promising non-petroleum alternative for the green production of ethylene (C2H4). However, server hydrogen evolution reaction (HER) competition in this process prominently decreases C2H4 selectivity, thereby hindering its practical application. Herein, a Cu-based composite catalyst, wherein porous carbon with nanoscale pores was used as a support, is constructed to gather the C2H2 feedstocks for suppressing the undesirable HER. As a result, the as-prepared catalyst exhibited C2H2 conversion of 27.1% and C2H4 selectivity of 88.4% at a C2H4 partial current density of 0.25 A/cm2 under optimal − 1.0 V versus reversible hydrogen electrode (RHE) under the simulated coal-derived C2H2 atmosphere, significantly outperforming the single Cu NPs counterparts. In addition, a series of in situ and ex situ experimental results show that not only the porous nature of the carbon support but also the stabilized Cu0–Cu+ dual active sites through the strong metal–support interactions enhance the adsorption capacity of C2H2, leading to high C2H2 partial pressure, restraining the HER and thus improving the C2H4 selectivity.
PubDate: 2024-07-23
- Chlorine-Substituent Regulation in Dopant-Free Small-Molecule
Hole-Transport Materials Improves the Efficiency and Stability of Inverted
Perovskite Solar Cells-
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Abstract: Abstract Although doped hole-transport materials (HTMs) offer an efficiency benefit for perovskite solar cells (PSCs), they inevitably diminish the stability. Here, we describe the use of various chlorinated small molecules, specifically fluorenone-triphenylamine (FO-TPA)-x-Cl [x = para, meta, and ortho (p, m, and o)], with different chlorine-substituent positions, as dopant-free HTMs for PSCs. These chlorinated molecules feature a symmetrical donor–acceptor–donor structure and ideal intramolecular charge transfer properties, allowing for self-doping and the establishment of built-in potentials for improving charge extraction. Highly efficient hole-transfer interfaces are constructed between perovskites and these HTMs by strategically modifying the chlorine substitution. Thus, the chlorinated HTM-derived inverted PSCs exhibited superior efficiencies and air stabilities. Importantly, the dopant-free HTM FO-TPA-o-Cl not only attains a power conversion efficiency of 20.82% but also demonstrates exceptional stability, retaining 93.8% of its initial efficiency even after a 30-day aging test conducted under ambient air conditions in PSCs without encapsulation. These findings underscore the critical role of chlorine-substituent regulation in HTMs in ensuring the formation and maintenance of efficient and stable PSCs.
PubDate: 2024-07-19
- Effective Activation of Melamine for Synchronous Synthesis of
Catalytically Active Nanosheets and Fluorescence-Responsive Quantum Dots-
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Abstract: Abstract Because of the low reactivity of cyclic nitrides, liquid-phase synthesis of carbon nitride introduces challenges despite its favorable potential for energy-efficient preparation and superior applications. In this study, we demonstrate a strong interaction between citric acid and melamine through experimental observation and theoretical simulation, which effectively activates melamine-condensation activity and produces carbon-rich carbon nitride nanosheets (CCN NSs) during hydrothermal reaction. Under a large specific surface area and increased light absorption, these CCN NSs demonstrate significantly enhanced photocatalytic activity in CO2 reduction, increasing the CO production rate by approximately tenfold compared with hexagonal melamine (h-Me). Moreover, the product selectivity of CCN NSs reaches up to 93.5% to generate CO from CO2. Furthermore, the annealed CCN NSs exhibit a CO conversion rate of up to 95.30 μmol/(g h), which indicates an 18-fold increase compared with traditional carbon nitride. During the CCN NS synthesis, nitrogen-doped carbon quantum dots (NDC QDs) are simultaneously produced and remain suspended in the supernatant after centrifugation. These QDs disperse well in water and exhibit excellent luminescent properties (QY = 67.2%), allowing their application in the design of selective and sensitive sensors to detect pollutants such as pesticide 2,4-dichlorophenol with a detection limit of as low as 0.04 µmol/L. Notably, the simultaneous synthesis of CCN NSs and NDC QDs provides a cost-effective and highly efficient process, yielding products with superior capabilities for catalytic conversion of CO2 and pollutant detection, respectively.
PubDate: 2024-07-08
- Corrosion-Resistant Polymer-Derived SiOC Membrane for Effective Organic
Removal via Synergistic Adsorption and Peroxymonosulfate Activation-
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Abstract: Abstract A major challenge is to construct ceramic membranes with tunable structures and functions for water treatment. Herein, a novel corrosion-resistant polymer-derived silicon oxycarbide (SiOC) ceramic membrane with designed architectures was fabricated by a phase separation method and was applied in organic removal via adsorption and oxidation for the first time. The pore structure of the as-prepared SiOC ceramic membranes was well controlled by changing the sintering temperature and polydimethylsiloxane content, leading to a pore size of 0.84–1.62 μm and porosity of 25.0–43.8%. Corrosion resistance test results showed that the SiOC membranes sustained minimal damage during 24 h exposure to high-intensity acid–base conditions, which could be attributed to the chemical inertness of SiOC. With rhodamine 6G (R6G) as the model pollutant, the SiOC membrane demonstrated an initial effective removal rate of 99% via adsorption; however, the removal rate decreased as the system approached adsorption saturation. When peroxymonosulfate was added into the system, efficient and continuous degradation of R6G was observed throughout the entire period, indicating the potential of the as-prepared SiOC membrane in oxidation-related processes. Thus, this work provides new insights into the construction of novel polymer-derived ceramic membranes with well-defined structures and functions.
PubDate: 2024-06-19
- Probing the Efficiency of PPMG-Based Composite Electrolytes for
Applications of Proton Exchange Membrane Fuel Cell-
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Abstract: Abstract PPMG-based composite electrolytes were fabricated via the solution method using the polyvinyl alcohol and polyvinylpyrrolidone blend reinforced with various contents of sulfonated inorganic filler. Sulfuric acid was employed as the sulfonating agent to functionalize the external surface of the inorganic filler, i.e., graphene oxide. The proton conductivities of the newly prepared proton exchange membranes (PEMs) were increased by increasing the temperature and content of sulfonated graphene oxide (SGO), i.e., ranging from 0.025 S/cm to 0.060 S/cm. The induction of the optimum level of SGO is determined to be an excellent route to enhance ionic conductivity. The single-cell performance test was conducted by sandwiching the newly prepared PEMs between an anode (0.2 mg/cm2 Pt/Ru) and a cathode (0.2 mg/cm2 Pt) to prepare membrane electrode assemblies, followed by hot pressing under a pressure of approximately 100 kg/cm2 at 60 °C for 5–10 min. The highest power densities achieved with PPMG PEMs were 14.9 and 35.60 mW/cm2 at 25 °C and 70 °C, respectively, at ambient pressure with 100% relative humidity. Results showed that the newly prepared PEMs exhibit good electrochemical performance. The results indicated that the prepared composite membrane with 6 wt% filler can be used as an alternative membrane for applications of high-performance proton exchange membrane fuel cell.
PubDate: 2024-06-06
- Fluorine-Doped High-Performance Li6PS5Cl Electrolyte by Lithium Fluoride
Nanoparticles for All-Solid-State Lithium-Metal Batteries-
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Abstract: All-solid-state lithium-metal batteries (ASSLMBs) are widely considered as the ultimately advanced lithium batteries owing to their improved energy density and enhanced safety features. Among various solid electrolytes, sulfide solid electrolyte (SSE) Li6PS5Cl has garnered significant attention. However, its application is limited by its poor cyclability and low critical current density (CCD). In this study, we introduce a novel approach to enhance the performance of Li6PS5Cl by doping it with fluorine, using lithium fluoride nanoparticles (LiFs) as the doping precursor. The F-doped electrolyte Li6PS5Cl-0.2LiF(nano) shows a doubled CCD, from 0.5 to 1.0 mA/cm2 without compromising the ionic conductivity; in fact, conductivity is enhanced from 2.82 to 3.30 mS/cm, contrary to the typical performance decline seen in conventionally doped Li6PS5Cl electrolytes. In symmetric Li SSE Li cells, the lifetime of Li6PS5Cl-0.2LiF(nano) is 4 times longer than that of Li6PS5Cl, achieving 1500 h vs. 371 h under a charging/discharging current density of 0.2 mA/cm2. In Li SSE LiNbO3@NCM721 full cells, which are tested under a cycling rate of 0.1 C at 30 °C, the lifetime of Li6PS5Cl-0.2LiF(nano) is four times that of Li6PS5Cl, reaching 100 cycles vs. 26 cycles. Therefore, the doping of nano-LiF offers a promising approach to developing high-performance Li6PS5Cl for ASSLMBs. Graphical 
PubDate: 2024-06-03
- Multi-objective Design of Blending Fuel by Intelligent Optimization
Algorithms-
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Abstract: Abstract Fuel design is a complex multi-objective optimization problem in which facile and robust methods are urgently demanded. Herein, a complete workflow for designing a fuel blending scheme is presented, which is theoretically supported, efficient, and reliable. Based on the data distribution of the composition and properties of the blending fuels, a model of polynomial regression with appropriate hypothesis space was established. The parameters of the model were further optimized by different intelligence algorithms to achieve high-precision regression. Then, the design of a blending fuel was described as a multi-objective optimization problem, which was solved using a Nelder–Mead algorithm based on the concept of Pareto domination. Finally, the design of a target fuel was fully validated by experiments. This study provides new avenues for designing various blending fuels to meet the needs of next-generation engines.
PubDate: 2024-05-08
- Review of Iron-Based Catalysts for Carbon Dioxide Fischer–Tropsch
Synthesis-
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Abstract: Abstract Capturing and utilizing CO2 from the production process is the key to solving the excessive CO2 emission problem. CO2 hydrogenation with green hydrogen to produce olefins is an effective and promising way to utilize CO2 and produce valuable chemicals. The olefins can be produced by CO2 hydrogenation through two routes, i.e., CO2-FTS (carbon dioxide Fischer–Tropsch synthesis) and MeOH (methanol-mediated), among which CO2-FTS has significant advantages over MeOH in practical applications due to its relatively high CO2 conversion and low energy consumption potentials. However, the CO2-FTS faces challenges of difficult CO2 activation and low olefins selectivity. Iron-based catalysts are promising for CO2-FTS due to their dual functionality of catalyzing RWGS and CO-FTS reactions. This review summarizes the recent progress on iron-based catalysts for CO2 hydrogenation via the FTS route and analyzes the catalyst optimization from the perspectives of additives, active sites, and reaction mechanisms. Furthermore, we also outline principles and challenges for rational design of high-performance CO2-FTS catalysts.
PubDate: 2024-04-09
- Coupling of BiOCl Ultrathin Nanosheets with Carbon Quantum Dots for
Enhanced Photocatalytic Performance-
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Abstract: Over the past few decades, photocatalysis technology has received extensive attention because of its potential to mitigate or solve energy and environmental pollution problems.Designing novel materials with outstanding photocatalytic activities has become a research hotspot in this field. In this study, we prepared a series of photocatalysts in which BiOCl nanosheets were modified with carbon quantum dots (CQDs) to form CQDs/BiOCl composites by using a simple solvothermal method. The photocatalytic performance of the resulting CQDs/BiOCl composite photocatalysts was assessed by rhodamine B and tetracycline degradation under visible-light irradiation. Compared with bare BiOCl, the photocatalytic activity of the CQDs/BiOCl composites was significantly enhanced, and the 5 wt% CQDs/BiOCl composite exhibited the highest photocatalytic activity with a degradation efficiency of 94.5% after 30 min of irradiation. Moreover, photocatalytic N2 reduction performance was significantly improved after introducing CQDs. The 5 wt% CQDs/BiOCl composite displayed the highest photocatalytic N2 reduction performance to yield NH3 (346.25 μmol/(g h)), which is significantly higher than those of 3 wt% CQDs/BiOCl (256.04 μmol/(g h)), 7 wt% CQDs/BiOCl (254.07 μmol/(g h)), and bare BiOCl (240.19 μmol/(g h)). Our systematic characterizations revealed that the key role of CQDs in improving photocatalytic performance is due to their increased light harvesting capacity, remarkable electron transfer ability, and higher photocatalytic activity sites. Graphical This work reports a novel CQDs/BiOCl composite photocatalyst for efficiently removing contaminants from water. 
PubDate: 2024-04-09
- Visible Light-Induced Photocatalysis: Self-Fenton Degradation of p-ClPhOH
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Abstract: Abstract Deep degradation of organic pollutants by sunlight-induced coupled photocatalytic and Fenton (photo-Fenton) reactions is of immense importance for water purification. In this work, we report a novel bifunctional catalyst (Fe-PEI-CN) by codoping graphitic carbon nitride (CN) with polyethyleneimine ethoxylated (PEI) and Fe species, which demonstrated high activity during p-chlorophenol (p-ClPhOH) degradation via H2O2 from the photocatalytic process. The relationship between the catalytic efficiency and the structure was explored using different characterization methods. The Fe modification of CN was achieved through Fe–N coordination, which ensured high dispersion of Fe species and strong stability against leaching during liquid-phase reactions. The Fe modification initiated the Fenton reaction by activating H2O2 into ·OH radicals for deep degradation of p-ClPhOH. In addition, it effectively promoted light absorption and photoelectron–hole (e–h+) separation, corresponding to improved photocatalytic activity. On the other hand, PEI could significantly improve the ability of CN to generate H2O2 through visible light photocatalysis. The maximum H2O2 yield reached up to 102.6 μmol/L, which was 22 times higher than that of primitive CN. The cooperation of photocatalysis and the self-Fenton reaction has led to high-activity mineralizing organic pollutants with strong durability, indicating good potential for practical application in wastewater treatment.
PubDate: 2024-04-06
- Highly Defective Dark TiO2 Modified with Pt: Effects of Precursor Nature
and Preparation Method on Photocatalytic Properties-
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Abstract: Abstract The study focused on the modification with platinum of dark defective titania obtained via pulsed laser ablation. Both the method of Pt introduction and the nature of the Pt precursor were varied. All samples exhibited similar phase compositions, specific surface areas, and Pt contents. High-resolution transmission electron microscopy coupled with pulsed CO adsorption revealed increased dispersity when photoreduction and the hydroxonitrate complex (Me4N)2[Pt2(OH)2(NO3)8] were used. The sample featured a high content of single-atom species and subnano-sized Pt clusters. The X-ray photoelectron spectroscopy results showed that the photoreduction method facilitated the appearance of a larger number of Pt2+ states, which appeared owing to the strong metal–support interaction (SMSI) effect of the transfer of electron density from the electron-saturated defects on the TiO2 surface to Pt4+. In the hydrogen evolution reaction, samples with a significant fraction of the Pt2+ ionic component, capable of generating short-lived Pt0 single-atom sites under irradiation due to the SMSI effect, exhibited the highest photocatalytic activity. The 0.5Pt(C)/TiO2–Ph sample exhibited the highest hydrogen yield with a quantum efficiency of 0.53, retaining its activity even after 8 h of operation.
PubDate: 2024-04-03
- Designing Membrane Electrode Assembly for Electrochemical CO2 Reduction: a
Review-
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Abstract: Currently, the electrochemical CO2 reduction reaction (CO2RR) can realize the resource conversion of CO2, which is a promising approach to carbon resource use. Important advancements have been made in exploring the CO2RR performance and mechanism because of the rational design of electrolyzer systems, such as H-cells, flow cells, and catalysts. Considering the future development direction of this technology and large-scale application needs, membrane electrode assembly (MEA) systems can improve energy use efficiency and achieve large-scale CO2 conversion, which is considered the most promising technology for industrial applications. This review will concentrate on the research progress and present situation of the MEA component structure. This paper begins with the composition and construction of a gas diffusion electrode. Then, the application of ion-exchange membranes in MEA is introduced. Furthermore, the effects of pH and the anion and cation of the anolyte on MEA performance are explored. Additionally, we present the anode reaction type in MEA. Finally, the challenges in this field are summarized, and upcoming trends are projected. This review should offer researchers a clearer picture of MEA systems and provide important, timely, and valuable insights into rational electrolyzer design to facilitate further development of CO2 electrochemical reduction. Graphical 
PubDate: 2024-04-03
- Optimizing Average Electric Power During the Charging of Lithium-Ion
Batteries Through the Taguchi Method-
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Abstract: Abstract In recent times, lithium-ion batteries have been widely used owing to their high energy density, extended cycle lifespan, and minimal self-discharge rate. The design of high-speed rechargeable lithium-ion batteries faces a significant challenge owing to the need to increase average electric power during charging. This challenge results from the direct influence of the power level on the rate of chemical reactions occurring in the battery electrodes. In this study, the Taguchi optimization method was used to enhance the average electric power during the charging process of lithium-ion batteries. The Taguchi technique is a statistical strategy that facilitates the systematic and efficient evaluation of numerous experimental variables. The proposed method involved varying seven input factors, including positive electrode thickness, positive electrode material, positive electrode active material volume fraction, negative electrode active material volume fraction, separator thickness, positive current collector thickness, and negative current collector thickness. Three levels were assigned to each control factor to identify the optimal conditions and maximize the average electric power during charging. Moreover, a variance assessment analysis was conducted to validate the results obtained from the Taguchi analysis. The results revealed that the Taguchi method was an effective approach for optimizing the average electric power during the charging of lithium-ion batteries. This indicates that the positive electrode material, followed by the separator thickness and the negative electrode active material volume fraction, was key factors significantly influencing the average electric power during the charging of lithium-ion batteries response. The identification of optimal conditions resulted in the improved performance of lithium-ion batteries, extending their potential in various applications. Particularly, lithium-ion batteries with average electric power of 16 W and 17 W during charging were designed and simulated in the range of 0–12000 s using COMSOL Multiphysics software. This study efficiently employs the Taguchi optimization technique to develop lithium-ion batteries capable of storing a predetermined average electric power during the charging phase. Therefore, this method enables the battery to achieve complete charging within a specific timeframe tailored to a specific application. The implementation of this method can save costs, time, and materials compared with other alternative methods, such as the trial-and-error approach.
PubDate: 2024-03-08
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